Not sure what you want to investigate yet? Browsing the shelves can be a good way to find that first spark of inspiration. Below are the general history call numbers to get you started. However keep in mind that history can be a highly interdisciplinary subject, so once you get started with the research process don't worry if your work takes you away from these numbers.
If this is your first time using the Library of Congress call numbers don't hesitate to ask a librarian for help.
Every research project starts with a question. Your question will allow you to select, evaluate and interpret your sources systematically. The question you start with isn’t set in stone, but will be revisited and revised as you read and interact with the sources.
Robert C. Williams suggests that a research question might:
Source: Williams, Robert C. The Historian's Toolbox: A Student's Guide to the Theory and Craft of History. Second ed. Armonk, NY: M. E. Sharpe, 2007.
Remember to publish your changes.